Isospin violating decays of vector charmonia

Abstract We study the isospin violating decays of vector charmonia to $$\Lambda \overline{\Sigma }^0$$ Λ Σ ¯ 0 and its charge conjugate. They are dominated by the single photon annihilation and can be evaluated reliably with timelike form factors. We utilize the quark-pair creation model, which is valid for the OZI suppressed decays, to evaluate the form factors. We obtain the branching fractions of $$\mathcal{B}(J/\psi \rightarrow \Lambda \overline{\Sigma }^0+c.c.)=(2.4\pm 0.4)\times 10^{-5}$$ B ( J / ψ → Λ Σ ¯ 0 + c . c . ) = ( 2.4 ± 0.4 ) × 10 - 5 and $$\mathcal{B}(\psi (2\,S)\rightarrow \Lambda \overline{\Sigma }^0+c.c.)=(3.0\pm 0.5)\times 10^{-6}$$ B ( ψ ( 2 S ) → Λ Σ ¯ 0 + c . c . ) = ( 3.0 ± 0.5 ) × 10 - 6 , which are compatible with the measurements by the BESIII collaborations, respectively. The decay asymmetries are found to be $$\alpha _{J/\psi }=0.314$$ α J / ψ = 0.314 and $$\alpha _{\psi (2S)}=0.461$$ α ψ ( 2 S ) = 0.461 , which can be examined at BESIII in the foreseeable future.